Crane Suzu: https://www.cranebellco.com/
Crane Suzu stem top cap mount: CRANE MINI SUZU TOP CAP BELL - BRASS
Crane Suzu headset spacer mount (spacer) http://www.cranebellusa.com/shop/product/crane-bell-suzu-mini-headset-mount-4150
Japan's trusty Crane Bell Co. has come along with these dandy little headset spacer-mount gems. 10mm spacer mount fits 1-1/8" or 1" threadless steerer w/ included shim.
To install, simply remove one 10mm headset spacer from your stack and replace it with the spacer-mount bell.
https://store.biketouringnews.com/crane-suzu-mini-headset-mount-bell/
https://www.modernbike.com/product-2126247050
PDW: https://www.youtube.com/watch?v=F9hyPbJTJBE
Knog Oi: https://www.knog.com/category/bike-bells/
http://www.mirrycle.com/incredibell_bells.php
http://www.mirrycle.com/brass_duet.php